Abstract
Background: Colorectal cancer (CRC) is one of the most common malignant tumors in the world, which has been introduced as the third most common cancer and the third leading cause of death. This cancer is uncommon before the age of 50. Its prognosis is controversial, and many studies report a poor prognosis in older patients, and the others show no difference. In addition to the factors, such as diet, environmental factors, somatic, and hereditary mutations, genetic factors, including altered expression of some microRNAs and mutations in tumor necrosis factor-α (TNF-α) gene, may be involved in CRC. Objectives: This study aimed to investigate the rs2910164 polymorphism from the miRNA146a gene and its association with the expression of TNF-α gene in CRC before and after the age of 50 for early diagnosis and treatment. Methods: In this study, 65 formalin-fixed paraffin-embedded (FFPE) tissue samples from patients with cancerous lesions of colorectal tissue (37 cases over 50 years were considered as the case group and 28 cases under 50 years were considered as the control group). DNA was extracted from the samples, and rs2910164 polymorphism of the miRNA146a gene was investigated by PCR. Moreover, RNA was extracted from the samples, and the expression of the miRNA146a and TNF-α genes were evaluated. Finally, Epi Info software version 7.1.3.10 and MedCalc Version 19.2.0 were used for data analysis. Results: The frequency of GG, GC, and CC genotypes from rs2910164 polymorphism of miRNA146a gene in the control group was 0.29, 0.46, and 0.25, respectively, but in the case group, it was 0.54, 0.38, and 0.08, respectively. The results also showed that the expression of miRNA146a (P = 0.00006) and TNF-α (P = 0.009) genes was higher in the case group than in the control group. Conclusions: Based on the results of this study, a significant correlation was found between GG genotype and rs2910164 polymorphism of miRNA146a gene and TNF-α gene expression in the CRC samples. Therefore, investigation of these factors may be helpful in patients with CRC over 50 years.